Can't go wrong with the E61 group head. It's the standard 58mm basket size, and it will be easy to find a good tamper for it.

Quick Mill also makes a similar line of machines.

The Expobar Lever is not really a "lever" machine. An Olympia Cremina or the Ponte Vecchio Lusso actually has a lever you pull on to make the shot. I believe the Expobar's lever just turns a solenoid on and off...